It is known to dispense concentrated chemical fluids by siphoning them through a venturi into a water stream and dispensing a flow of mixed water and chemicals. Mixers known as eductors, aspirators or proportioners accomplish this task by providing a water flow through a venturi section and siphoning chemicals into the flow through a low pressure orifice in the venturi section. Such eductors are useful in a number of applications, such as in dispensing diluted cleaning agents for cleaning procedures.
In these proportioning systems, it is important to maintain the water source free of cross-connection so that the chemicals are not drawn back into the water source. This has been accomplished through the use of integrated backflow preventers such as air gap eductors, hose connection vacuum breakers, atmospheric vacuum breakers, pipe interrupters and elastomer gap eductors (e-gaps). In a typical application, such air gap eductors include a nozzle upstream of the venturi section for defining a stream of water flowing across an unobstructed gap in the eductor body prior to entering the venturi section. Upon any water shutdown or pressure reversal in the water system, the water stream terminates, leaving a gap in the eductor between the nozzle and the venturi section where the chemical is otherwise first introduced. There is thus no mechanism capable of transmitting chemicals back to the nozzle or upstream in the water supply. Forms of air gap eductors are disclosed, for example, in U.S. Pat. Nos. 5,519,958; 5,522,419; 5,253,677 and 5,862,829. Whichever the type of backflow preventer used, the chemicals are prevented from flowing back into the water supply. In these proportioning systems, water regulatory authorities do not permit shutoff valves to be located downstream of the backflow protectors.
The eductor in a proportioning apparatus is typically connected to a discharge tube or hose for dispensing the fluid. One use for the apparatus is to fill a mop bucket or a floor scrubbing machine. For this use, a user must hold the discharge tube in one hand and activate the dispenser with the other hand. This two-handed operation is not user friendly, particularly where the dispenser is tucked into a small custodial closet where it is connected to the water source thereby making it difficult to dispense the fluid from a distance greater than the operator's arm span. It is thus desirable to have a dispensing or proportioning apparatus capable of dispensing fluid without the operator being near the dispenser, but which also meets regulatory requirements for chemical backflow protection and shut-off valves.